There has long been a need to locate leaks in closed refrigeration systems, originally because the loss of refrigerant reduces the cooling capacity of the system, and increasingly because the refrigerants themselves are potential hazardous or deleterious substances when released to the atmosphere. In particular, the production and use of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants is scheduled for incremental phaseout, and for recovery and recycling in the interim.
Various methods have been used for detecting and locating leaks in a refrigeration system. Since a slow leak of refrigerant is essentially silent and invisible, such methods have included halide torches, electronic sensors, coating exterior joints with material which reacts with the refrigerant, and injecting various types of dye into the refrigeration equipment to locate sites where the dye exits the system.
One of the most effective methods for detecting leaks in refrigeration systems, and a preferred method to be practiced with the present invention, comprises infusing into the refrigeration system an effective amount of a fluorescent dye compound, dissolved either in the system lubricating oil or in a mixture of the oil and refrigerant. The dye compound circulates with the refrigerant and oil throughout the refrigeration circuit, and is carried out with escaping refrigerant and oil at a leak site. When the refrigeration system is exposed to ultraviolet light, even a small deposit of the dye compound is brilliantly fluorescent to allow visual detection of the leak. U.S. Pat. No. 5,149,453 discloses such a method for detecting leaks in a refrigeration system, and its content is incorporated herein by reference.
When practicing the above method of leak detection with a fluorescent dye, care has to be taken that the fluorescent dye additive is not allowed to contact the exterior of the refrigeration system as the dye is being introduced into the system. If dye additive is inadvertently spilled or rubbed on the exterior of the system, it will be difficult to distinguish between fluorescence from a leak site and that resulting from inadvertent external contact. This is a particular concern where the dye additive is used for quality assurance checks of air conditioners on newly assembled automobiles, as the air conditioning system's final assembly is usually completed in the automobile assembly line, after which the system is charged with refrigerant and leak detection additive, then operated to circulate the additive and reveal any leaks when viewed under ultraviolet light. While care is normally taken to prevent the refrigerant, lubricant and dye from escaping, the nature of the assembly and charging process creates a risk of spills or inadvertent contamination on clothing or tools. Since very low concentration of dye is required to produce fluorescence, any dye, dyed refrigerant or oil spilled or rubbed on the exterior of the air conditioning system may cause false leak indications.
In addition, the number of dyes that can be used are limited to those dyes which are sufficiently soluble in order to allow the dye to be placed in a concentrated liquid. The concentrate liquid is necessary to inject the dye into the refrigeration system. Furthermore, the concentrated liquid must have a sufficient concentration of the dye to be adequately fluorescent under ultra-violet illumination when mixed with the entire refrigeration system.
Consequently, it would be desirable to have a method of introducing leak detection dye into the air conditioning system prior to the initial charging of the system, as this expedient would virtually eliminate any possibility of inadvertent dye contact to the exterior of the air conditioner and allow for increased selection of dyes which can be used.
For that reason, an objective and advantage of the present invention is a method by which the leak detection dye additive is installed in an air conditioning or other refrigeration system before the system is charged with refrigerant. The leak detection dye is released into the refrigerant immediately after the system is charged and operated, in order to reduce the risk of inadvertent contact of the dye on the outside of the system and yet permit quality control leak testing after charging, and remains in the system to permit subsequent leak detection.
Another objective and advantage of the present invention is a method which allows leak detection dye additive to be installed and stored in a component of the air conditioning system well prior to assembly of the complete system.
Another objective and advantage of the present invention is a method to pre-install a specific quantity of dye additive which is proportional to the amount of initial charge of the refrigeration or system lubricant, to ensure that a predictable concentration of dye will be introduced.
Further objects, features and advantages of the present invention, will become apparent to those skilled in the art as the invention is more fully understood by reading the accompanying drawings and detailed descriptions.